Inner-west residents are bracing for severe weather and widespread flooding as once-in-a-generation rain rain bears down on Melbourne and Victoria.

A flood warning has been issued for the Maribyrnong River and a severe weather warning for heavy rain remains current for the entire state.

Up to 100mm of rain could fall on Melbourne today and tomorrow, with heavy rain also expected on Sunday.

Rain moves into Melbourne on Friday. Image via Bureau of Meteorology

Rain moves into Melbourne on Friday. Image via Bureau of Meteorology

Significant stream rises are expected, with widespread flooding likely from Friday onwards in catchments including the Maribyrnong, Yarra and Werribee Rivers.

Authorities are warning of the need for extreme caution around waterways in what could be the state’s most significant rain event in more than 20 years.

Flooding in Altona in 2014.

Flooding in Altona in 2014.

Friday’s rain is expected to bring flash flooding while the rivers are likely to continue rising over the weekend as more rain falls and enters the catchment.

Rainfall is expected to exceed that which caused Maribyrnong to flood in 2011 and large parts of Altona and Seaholme to be submerged in 2014.

Homes were flooded along the Esplanade during the 2014 storm surge, which caused more than half a million damage to the foreshore from Apex Park to Cresser Reserve.

Motorists are being warned not to try to cross Altona ford as Kororoit Creek rises. Photo by Kathryn Hocking

Motorists are being warned not to try to cross the Racecourse Road ford as Kororoit Creek rises. Photo by Kathryn Hocking

The State Emergency Service says the Maribyrnong flood plain is comprised of 400 properties including commercial, residential and community facilities which are threatened by large river events in the order of 1 in 100 year events.

Flood Management Plans have been completed for Hobsons Bay  and Maribyrnong Council, along with a Local Flood Guide.

 

Altona Beach as storms rolled in on Thursday. Photo: Karl J Zeller

Altona Beach as storms rolled in on Thursday. Photo: Karl J Zeller

 

In Hobsons Bay,flash flooding can also be an issue, especially during high tides when water cannot drain away.

Areas that could be affected include McIntyre Drive, Civic Parade and the area between Civic Parade and the railway line from Seves Street.

During longer rain events Laverton Creek, Cherry Lake and Kororoit Creek can flood large areas as excess water from north of Altona drains into the sea.